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//===-- ConstantFolding.cpp - Analyze constant folding possibilities ------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This family of functions determines the possibility of performing constant
// folding.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
#include <cerrno>
#include <cmath>
using namespace llvm;
//===----------------------------------------------------------------------===//
// Constant Folding ...
//
/// canConstantFoldCallTo - Return true if its even possible to fold a call to
/// the specified function.
bool
llvm::canConstantFoldCallTo(Function *F) {
const std::string &Name = F->getName();
switch (F->getIntrinsicID()) {
case Intrinsic::isunordered_f32:
case Intrinsic::isunordered_f64:
case Intrinsic::sqrt_f32:
case Intrinsic::sqrt_f64:
case Intrinsic::bswap_i16:
case Intrinsic::bswap_i32:
case Intrinsic::bswap_i64:
// FIXME: these should be constant folded as well
//case Intrinsic::ctpop_i8:
//case Intrinsic::ctpop_i16:
//case Intrinsic::ctpop_i32:
//case Intrinsic::ctpop_i64:
//case Intrinsic::ctlz_i8:
//case Intrinsic::ctlz_i16:
//case Intrinsic::ctlz_i32:
//case Intrinsic::ctlz_i64:
//case Intrinsic::cttz_i8:
//case Intrinsic::cttz_i16:
//case Intrinsic::cttz_i32:
//case Intrinsic::cttz_i64:
return true;
default: break;
}
switch (Name[0])
{
case 'a':
return Name == "acos" || Name == "asin" || Name == "atan" ||
Name == "atan2";
case 'c':
return Name == "ceil" || Name == "cos" || Name == "cosf" ||
Name == "cosh";
case 'e':
return Name == "exp";
case 'f':
return Name == "fabs" || Name == "fmod" || Name == "floor";
case 'l':
return Name == "log" || Name == "log10";
case 'p':
return Name == "pow";
case 's':
return Name == "sin" || Name == "sinh" ||
Name == "sqrt" || Name == "sqrtf";
case 't':
return Name == "tan" || Name == "tanh";
default:
return false;
}
}
Constant *
llvm::ConstantFoldFP(double (*NativeFP)(double), double V, const Type *Ty) {
errno = 0;
V = NativeFP(V);
if (errno == 0)
return ConstantFP::get(Ty, V);
return 0;
}
/// ConstantFoldCall - Attempt to constant fold a call to the specified function
/// with the specified arguments, returning null if unsuccessful.
Constant *
llvm::ConstantFoldCall(Function *F, const std::vector<Constant*> &Operands) {
const std::string &Name = F->getName();
const Type *Ty = F->getReturnType();
if (Operands.size() == 1) {
if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) {
double V = Op->getValue();
switch (Name[0])
{
case 'a':
if (Name == "acos")
return ConstantFoldFP(acos, V, Ty);
else if (Name == "asin")
return ConstantFoldFP(asin, V, Ty);
else if (Name == "atan")
return ConstantFP::get(Ty, atan(V));
break;
case 'c':
if (Name == "ceil")
return ConstantFoldFP(ceil, V, Ty);
else if (Name == "cos")
return ConstantFP::get(Ty, cos(V));
else if (Name == "cosh")
return ConstantFP::get(Ty, cosh(V));
break;
case 'e':
if (Name == "exp")
return ConstantFP::get(Ty, exp(V));
break;
case 'f':
if (Name == "fabs")
return ConstantFP::get(Ty, fabs(V));
else if (Name == "floor")
return ConstantFoldFP(floor, V, Ty);
break;
case 'l':
if (Name == "log" && V > 0)
return ConstantFP::get(Ty, log(V));
else if (Name == "log10" && V > 0)
return ConstantFoldFP(log10, V, Ty);
else if (Name == "llvm.sqrt.f32" || Name == "llvm.sqrt.f64") {
if (V >= -0.0)
return ConstantFP::get(Ty, sqrt(V));
else // Undefined
return ConstantFP::get(Ty, 0.0);
}
break;
case 's':
if (Name == "sin")
return ConstantFP::get(Ty, sin(V));
else if (Name == "sinh")
return ConstantFP::get(Ty, sinh(V));
else if (Name == "sqrt" && V >= 0)
return ConstantFP::get(Ty, sqrt(V));
else if (Name == "sqrtf" && V >= 0)
return ConstantFP::get(Ty, sqrt((float)V));
break;
case 't':
if (Name == "tan")
return ConstantFP::get(Ty, tan(V));
else if (Name == "tanh")
return ConstantFP::get(Ty, tanh(V));
break;
default:
break;
}
} else if (ConstantUInt *Op = dyn_cast<ConstantUInt>(Operands[0])) {
uint64_t V = Op->getValue();
if (Name == "llvm.bswap.i16")
return ConstantUInt::get(Ty, ByteSwap_16(V));
else if (Name == "llvm.bswap.i32")
return ConstantUInt::get(Ty, ByteSwap_32(V));
else if (Name == "llvm.bswap.i64")
return ConstantUInt::get(Ty, ByteSwap_64(V));
}
} else if (Operands.size() == 2) {
if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
double Op1V = Op1->getValue();
if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
double Op2V = Op2->getValue();
if (Name == "llvm.isunordered.f32" || Name == "llvm.isunordered.f64")
return ConstantBool::get(IsNAN(Op1V) || IsNAN(Op2V));
else
if (Name == "pow") {
errno = 0;
double V = pow(Op1V, Op2V);
if (errno == 0)
return ConstantFP::get(Ty, V);
} else if (Name == "fmod") {
errno = 0;
double V = fmod(Op1V, Op2V);
if (errno == 0)
return ConstantFP::get(Ty, V);
} else if (Name == "atan2")
return ConstantFP::get(Ty, atan2(Op1V,Op2V));
}
}
}
return 0;
}
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